In various ink jet recording systems, a so-called an electrostatic ink-jet by utilizing electrostatic force, with which the present invention is concerned, can form very high precise images by combining with an organic solvent-based ink composition.
On the other hand, the ink jet recording system has such faults as clogging of nozzles, clogging of filters, change of ink compositions with the passage of time, etc., and well as other fault that the system is liable to cause abnormal ejection by various factors, which are the largest causes of obstructing the propagation of the system.
In electrostatic ink-jet system, with which the present invention is concerned, obtaining stable jetting largely influences on the reliability of the system as in other systems, and for the purpose, there are proposed the viscosity and specific resistance of an ink composition as properties in Japanese Patent Application (OPI) No. 50935/74 and the relative dielectric constant and specific resistance of a solvent for an ink composition as the properties in Japanese Patent Application (OPI) No. 29808/78. The term "OPI" as used herein indicates an "unexamined published Japanese patent application".
Also, in regard to ink compositions for general ink jet printer, for stabilizing the dissolution or dispersion of color materials being used, ink compositions using improved solvents are proposed in Japanese Patent Application (OPI) Nos. 3443871/82, 78050/80, 3871/82, 3873/82, and 36381/86. However, according to the inventor's experiments, these ink compositions not always give stably ejecting inks in electrostatic ink-jet system with which the present invention is concerned.